Internal-combustion engine



Jan. 8, 1946. HURST 2,392,591

INTERNAL-COMBUSTION ENGINE Filed July 31, 1940 lnvenfor Patented Jan. 8-, 1946 INTERNAL-COMBUSTION ENGINE Max Hurst, steam Germany; vested in the Alien Property Custodian Application July 31, 1940, Serial No. 348,728 In Germany September 1, 1939 2 Claims. -(Cl. 123-139) This invention relates to an injection system for internal combustion engines in which the distribution of fuel is controlled by the compression of the air in the engine cylinders.

In the known internal combustion engines of the fuel injection type in which the air compression in the engine cylinders is made use of for controlling the injection nozzles the beginning of injection is determined by the compression pressure. As this pressure of the compressed air is subject to fluctuations, the beginning of injection is irregular.

lib, c, 611 which lead to the injection valves. For

- each cylinder Z an injection valve is provided According to the present invention, the beginning of injection of fuel into a cylinder ready to receive a fuel charge is determined by the existence of a compression pressure in that cylinder, supplemented by the pressure of the fuel coming from the fuel injection pump, both pressures acting simultaneously to open the injection nozzle of the cylinder at the right time. In a multicyllnder engine the invention contemplates providing a single pump for two or more cylinders, connected to such cylinders by a, manifold, with the compression pressure and the fuel injection pressure cooperating to determine which of the cylinders will be charged with fuel to the exclusion of others, at any point in the cycle of operation of the engine in proper order. done by connecting the outlet of a single cylinder injection pump performing one delivery stroke for each working stroke of the engine with the various nozzles by a, correspondingly branched pressure piping and interposed shut-off members which are so controlled by the compression pressure developed in the associated cylinder that the fuel supplied by the pump at each stroke can be injected only into the cylinder whose piston performs the next power stroke,

Three embodiments of the invention are diagrammatically illustrated in the accompanying drawing, in which Figure 1 shows an injection system according to the invention for a four cylinder internal combustion engine of the four stroke cycle type;

Fig. 2 shows an injection valve diifering from the one shown in Fig. 1; and

Fig. 3 another form of injection valve with shu on means.

The numeral I designates an injection'pump, partly shown in section, whosepiston 2 forces at each stroke a regulatable amount of fuel into a pipe 3, regulation being effected in known man- 'ner by turning the piston which has an inclined control face. The pipe 3 terminates in branches 4a, 4b which in turn branch oil into conduits 5a,

This iscomprising a casing 6 possessing a longitudinal bore 1. in which a slide 8 moves which has a bore 9 extending in the lower part thereof and terminating adjacent the lower end of the slide in injection holes ll formed in a head 10. The upper end of the bore 8 terminates in a transverse bore i2 formed through the slide 8. The slide 8 terminates at its upper end in a collar it which normally rests upon an interior shoulder l5 formed in the casing 6, in which position it is yleldably held by a helical spring l4 compressed between the upper end of the slide and the top of the casing. In this normal position of the slide the head it and the lower part of the slide depends into the interior of the cylinder Z and the portion of the slide above the transverse bore l2 closes the fuel passage is which is formed laterally through the casing and has the corresponding one of the pump manifold conduits connected thereto.

When one of the pistons I'I during its compression stroke approaches its upper dead center, the compression pressure works against the exposed lower part of the slide 8 and elevates the slide against the tension of the spring it until the head l0 abuts the casing in which position the transverse bore I2 is registered with the fuel passage IB whereby the nozzle aperture is in communication with the fuel pump, and the fuel injection into the cylinder then follows.

Since the engine shown in Fig. 1 is of the four cylinder four stroke cycle type, two cylinders require fuel at .each revolution of the crankshaft. The pump shaft driven by the engine at crankshaft speed is provided with a double cam l8, 1. e. v

a cam having two operating edges, so that the piston of the pump carries out two suction and pressure strokes at each revolution of the shaft.

In case of a four cylinder two stroke cycle engine, either the double cam of the injection pump would have to move twice as fast as the crankshaft or, if the pump shaft is to move at the same speed as the crankshaft of the engine, a cam having four operating edges would be required with the throws of the cranks displaced relative to one another.

The injection valve shown in Fig. 2 diflers from the one shown in Fig. 1 in that the injection holes II are provided in the valve casing B instead of in the slide. The slide valve I 9 worked in opposite directions by the cylinder compression and the force of the spring it merely controls the communication of the pressure pipe with a passage 2t in the casing 6, which remains open as long as the slide is is in the raised position by compression pressure in the cylinder.

The injection valve shown in Fig. 3 possesses a jet needle 2| whose shoulder 22 is acted on by the fuel pressure prevailing in the pipe 3, l, 5 and which tends to raise the needle 2| from its seat in the opening direction against the tension of a closing spring 23 which is strong enough to resist either the injection fuel pressure or the cylinder compression pressure. The cylinder compression pressure acts by itself through a passage 24 leading from the interior of the cylinder I into an annular space 25 formed in the valve casing below the valve shoulder 26 provided by the collar 21. However, the combined raising eflect upon the valve or slide I 9 of both the cylinder compression pressure and the pressure of the incoming fuel is sufllcient to overcome the spring 23 and raise the valve to the open position and produce an injectionof fuel into the cylinder.

It will be obvious from the foregoing that while the injection valves shown in Figures 1'- and 2 are opened for injection by the pressure in the cylinder occurring on a compression stroke of the piston in the cylinder. the injection valve shown in Figure 3 requires in addition to the compression pressure the pressure of the fuel coming from the injection pump to open the injection valve.

I declare that what I claim is:'

1. A fuel injector for aninternal combustion engine having a working cylinder and a pressure fuel supply, said injector comprising a valve body. a valve reciprocably mounted therein, spring means normally closing the valve, a fuel passage in the valve body connected with said pressure fuel supply and a fuel injection chamber formed in said body around the valve, and provided with an aperture leading into the interior of the cyl inder, said aperture being closed by a portion of the valve in its closed position, a compression pressure chamber formed in said body around the valve in longitudinally spaced relation to the injection chamber and having direct communication with the interior of the cylinder, the portions of the valve within the fuel injection and compression pressure chambers having enlargements against which the fuel pressure and the compression pressure, respectively, act, said spring means being strong enough to resist the valve opening influences of either of said pressures alone but yieldable to the combined exertion of these pressures on said enlargements to permit opening of the valve.

2. A fuel injector for an internal combustion engine having a working cylinder and a pressure fuel supply, said injector comprising a valve body and a spring closed valve operable therein to connect and disconnect the fuel supply with the interior of the cylinder in response to compression and non-compression phases in the cylinder, said valve body and valve being cooperatively formed to provide two separate pressure responsive zones, one of which is acted on by the fuel pressure and the other by compression pressure in the engine cylinder, the valve closing spring being sufliciently tensioned to resist opening of the valve by either pressure alone, but insufficiently tensioned to resist opening of the valve by the combined exertion of the two pressures.

MAX HURST. 

